This invention relates to alarm locks, that is to say, locking devices including built-in alarm systems, and particularly to portable locking devices adapted for attachment to articles such as bicycles, motor-bikes and the like, to prevent them from being stolen.
Various types of alarms of this kind have been proposed previously, but their mechanical construction is frequently complicated, for example by requiring special lock mechanisms, and very often, they are not as robust as the simple "U-bar" or "padlock type" locking device.